Hideyuki Oguro will join the Cell Biology Department in September 2020, as an assistant professor, with a joint appointment in the Department of Obstetrics and Gynecology. His research concerns mechanisms that regulate hematopoietic stem cells, and investigates how in conditions where more blood is needed, hormonal signals stimulate the proliferation and mobilization of these stem cells to make more blood cells. In a recent paper (J. Clinical Investigation, 2017, 127: 3392-2401), Oguro and colleagues demonstrated that two endogenous estrogen receptor ligands, estradiol and 27-hydroxycholesterol, differentially induce proliferation and mobilization of hematopoietic stem cells, respectively. This hormonal regulation is particularly important during pregnancy when maternal blood expands rapidly (figure adopted from Frontiers in Endocrinology, 2019, 10:204), and can lead to new strategies to promote hematopoietic regeneration and to enhance mobilization of stem cells into the bloodstream for transplantation. An additional focus of Oguro’s research is to generate hematopoietic stem cells from human induced pluripotent stem cells by mimicking their developmental process.